This invention relates to a bearing clearance detector or probe and, more particularly, to a method and apparatus for facilitating the determination of engine bearing clearances without the necessity of disassembling the engine.
In our U.S. Pat. No. 4,928,400 entitled BEARING CLEARANCE DETECTOR, a probe is described and illustrated which is used for the purpose of determining the clearances between initially, a piston and its piston rod and, secondly, between the piston rod and the crank pin of a crank shaft without the necessity of disassembling the engine. In order to obtain such clearances, a probe is inserted through a cylinder hole allowing access to the piston such as a spark plug, injector, airstart valve or fuel gas valve hole. An incremental vacuum sufficient to raise the piston relative to the piston rod is applied to the probe and the distance through which the piston moves as,measured by a measuring device such as a dial indicator. Thereafter, a further vacuum is applied to the probe sufficient to lift the piston and the piston rod relative to the crank pin. This second distance through which the piston and piston rod move is also measured. The two distances are readily obtained without disassembling the engine.
In the aforementioned measurement, however, it is necessary that the xe2x80x9cstepxe2x80x9d between the two measured distances be readily observable in order that the distance moved by the piston relative to the piston rod and the distance moved by the piston and piston rod relative to the crank pin can be accurately differentiated. In utilizing the probe, a vacuum line is connected directly to the instrument and the measurement device, conveniently a dial indicator. The operator of the line through which the vacuum is applied is, however, separated from the instrument itself with the result that two man operation and coordination between them was necessary. This is an unnecessarily expensive undertaking and, in addition, because of the lack of xe2x80x9chands onxe2x80x9d operation between the individual reading the gauge and the individual operating the vacuum or air pressure line, it is difficult to tell precisely when the xe2x80x9cstepxe2x80x9d or second incremental movement of the piston occurred. The eventual result was correct but unnecessary time was consumed.
The necessity for accurate coordination between vacuum and pressure application and the reading of the dial indicator is particularly important in vee-type engines having master and link rods. This is so because one side of the engine has no inspection openings or xe2x80x9cdoorsxe2x80x9d and inspection of the link rod bearings is impossible without major dismounting of the engine.
According to one aspect of the invention, there is provided a bearing clearance detector operable to be inserted into a hole of the cylinder of an engine, a distance measuring device operably connected to said detector and operating apparatus interposed between an air supply line connected to said detector and a source of air pressure supplied to said operating apparatus, said operating apparatus including means to incrementally apply a vacuum to said cylinder of said engine while allowing an operator of said incremental application means to observe the distance measuring device connected to said detector.
According to a further aspect of the invention, there is provided a method of applying a vacuum or air pressure to a bearing clearance detector comprising applying air pressure to said detector, applying increasing vacuum to said detector while observing the distance indicated on a measurement device operably connected to said detector.